sneaker (n.)

1550s (implied in sneakish), "creep or steal about privately; move or go in a stealthy, slinking way" (intransitive); perhaps from some dialectal survival of Middle English sniken "to creep, crawl" (c. 1200), which is from Old English snican "to sneak along, creep, crawl," from Proto-Germanic *sneikanan, which is related to the root of snail and snake (n.).

The transitive sense of "insert stealthily" is by 1640s. That of "partake of or get surreptitiously" is from 1883. Related: Sneaking. To sneak up on someone or something is by 1869.

As an adjective, in reference to feelings, suspicions, etc., "not openly vowed, undemonstrative," from 1748. Sneak-thief, one who enters through unsecured doors and windows to steal, is recorded by 1859; the movies sneak-preview of a film before official release is from 1938.

"mark on the hull of a British ship showing how deeply she may be loaded," 1876 (Plimsoll's mark), from Samuel Plimsoll (1824-1898), M.P. for Derby and advocate of shipping reforms (which were embodied in the Merchant Shipping Act of 1876 and required the load-line mark).

The sense was extended by 1907 to rubber-soled canvas shoe (equivalent of American English sneakers) because the band around the shoes that holds the two parts together reminded people of a ship's Plimsoll line; this sense perhaps also was reinforced by sound association with sole (n.1), which sometimes influenced the spelling to plimsole. The surname is of Huguenot origin.

"sticky," 1788, from tack (n.1) in the sense of "an act of attaching temporarily" + -y (2). Related: Tackiness "stickiness."